Duplex ultrasound-guided angioplasty of hemodialysis vascular access.

OBJECTIVE: Duplex ultrasound-guided angioplasty (DA) for hemodialysis vascular accesses remains questionable regarding its feasibility and safety. Minor complications (requiring no more treatment than nominal therapy) might be over-reported. Our hypothesis is that this procedure has no significant differences between observed rates and the recommended threshold of main outcomes of the procedure defined by the standards of arteriovenous fistulas (AVF) angioplasty. METHODS: In a single-center retrospective study, 298 DA performed on 141 patients from 2015 to 2019 were analyzed. Occluded AVF or concomitant use of radiographic guidance were excluded. Duplex ultrasound parameters were collected up to 1 month before, at the end of angioplasty, and on day 30 after the procedure. Complications were registered, and patency rates were studied at 24 months of follow-up. RESULTS: Anatomical success was achieved in 142 procedures (47.7%), clinical success in 284 (95.3%), and hemodynamic success in 283 (95.0%). Major complications-requiring at least a specific therapy-were reported in 8 procedures (2.7%) and minor complications-requiring no adjunctive therapy-in 157 (52.7%). At 24 months, overall postintervention primary patency was 34.0%, primary-assisted patency 87.4%, and secondary patency 92.5%. There were no significant differences of patency rates between groups with or without minor complications (P value for primary patency, 0.08; primary-assisted patency, 0.08; secondary patency, 0.23) or 30% residual stenosis (P value for primary patency, 0.82; primary-assisted patency, 0.46; secondary patency: 0.63). Duplex parameters further improved at postoperative day 30 after angioplasty. CONCLUSIONS: DA of AVF is feasible, safe-despite over-reported minor complications having no impact on postintervention patency rates-and efficient. A minor complication can be seen as an event without bad or good consequences. Anatomical definition of success does not fit on DA for hemodialysis vascular access. Further studies are required to define the duplex parameter threshold for efficacy.

Innovations thérapeutiques dans la prise en charge de l'anémie de la maladie rénale chronique Therapeutic innovations in the management of chronic kidney disease-associated anemia.

Anemia is a common complication of chronic kidney disease (CKD). The insufficient erythropoietin (EPO) production by the kidneys and iron deficiency are the main causes. Iron supplementation and the administration of recombinant EPO are the main treatment modalities. New iron formulations that can be administered orally, intravenously or directly via the dialysate have recently been developed to improve efficacy and tolerance. Ferric citrate administered orally can effectively corrects anemia in case of iron deficiency and in addition chelate phosphate in the gut lumen. Ferric carboxymaltose allows intravenous administration of larger doses given less frequently. Ferric pyrophosphate citrate administered directly via the dialysate allows the compensation of iron losses during the hemodialysis session. HIF-prolyl-hydroxylase inhibitors are a new therapeutic class of erythropoiesis-stimulating agents. Orally administered, they act by stabilizing the HIF transcription factor involved in the initiation of erythropoietin production by hypoxia. Several clinical studies have recently evaluated these new molecules in comparison with recombinant EPO. In CKD patients not yet on dialysis or undergoing dialysis therapy non-inferiority in correcting anemia has been demonstrated compared with recombinant EPO. The decrease in circulating hepcidin they induce appears greater than that induced by injectable recombinant EPO. Presently available reports on the safety of HIF-prolyl-hydroxylase inhibitors are reassuring but need to be confirmed in longer-term studies of larger size. © 2022 Published by Elsevier Masson SAS on behalf of Société francophone de néphrologie, dialyse et transplantation.

Rheopheresis: A narrative review.

INTRODUCTION: Rheopheresis is an extracorporal selective double-filtration procedure with an initial separation of plasma from the whole blood and a further filtration of the plasma through a second filter in order to eliminate a certain number of high molecular weight proteins such LDL, Lp(a), fibrinogen, α2-macroglobulin, Factor von Willebrand, and IgM Immunoglobulin. METHODS: In this narrative review we discuss the available data on the effects of Rheopheresis in various clinical conditions. RESULTS: Rheopheresis is considerd to exert a rapid effect on clinical conditions associated with seriously affected microcirculation and rheologic parameters such as, the dry age-related macular degeneration (AMD), sudden sensorineural hearing loss (SSHS), peripheral artery disease (PAD), calciphylaxis, systemic sclerosis and diabetic foot. CONCLUSIONS: Rheopheresis is a promising technique for conditions associated with affected microcirculatory rheologic parameters.

Identifying the performance and losses of a scroll compressor with vapour injection and R1234ze(E).

This work investigates a vapour injection scroll compressor integrated in a heat pump using the refrigerant R1234ze(E). The water-to-water heat pump was tested under a wide temperature range at the evaporator and condenser sides. The test results revealed that the performance is significantly reduced for lifts of over 30 K with the coefficient of performance being even below 2 and the maximum 2 nd law efficiency was just 28%. In order to enlighten the reasons behind such significant compressor underperformance, a semi-empirical model has been extended to include vapour injection, and a new improved modelling approach for the suction pressure drop was developed and implemented considering both the turbulent and laminar inlet flow regimes. Once the accuracy of the developed semi-empirical model was verified, the model was then adjusted to account for the R1234ze(E) operation, by fine-tuning its parameters based on the test data. The main loss mechanism identified is the high suction pressure drop, due to the high friction factor, with the inlet refrigerant flow possibly being laminar instead of turbulent. This resulted in a significant reduction of the mass flow rate and volumetric efficiency, while the standard model for suction pressure drop was not able to capture this effect.

A Retrospective Comparison of Patient and Pressure Injury Data at Two Time Points in a Regional Hospital in France.

BACKGROUND: Pressure injuries (PIs) are a significant problem for health care institutions. PURPOSE: A retrospective study of patient data was conducted at a semi-urban state hospital in France, aiming to evaluate the rate of PIs and variables that may influence PI prevalence and care at 2 different time points. METHODS: Patient demographic, clinical, PI and PI prevention, and care variables were retrieved from the charts of all patients on all wards (except pediatrics and obstetrics) on October 20, 2009, and on October 24, 2013-4 years apart. Qualitative data were compared between the 2 dates using a t-test for independent variables. The remaining variables were compared using Pearson's chi-square method. P < .05 was considered significant. RESULTS: No significant differences were noted in PI rates (19% for 2009 and 16% for 2013) or the timing of their occurrence (51% occurred following admission in 2009, and 58.3% occurred after admission in 2013). Significant differences were found with regard to patient age (average, 73.97 and 76.22 years old in 2009 and 2013, respectively; P = .014) and rates of serious injuries (27% and 43% were stages 3 and 4 in 2009 and 2013, respectively; P = .010). Compared with 2009, in 2013, significantly more patients were placed on a specialty mattress and provided nutritional supplements and fewer were provided percutaneous endoscopic gastrostomy or nasogastric tubes. CONCLUSION: The rate of PIs was not different between these 2 time points despite improvements in the use of preventive and therapeutic measures, perhaps due to the increased age and frailty of the patient population in 2013 compared with 2009. Additional prospective research across multiple health care entities is warranted.

Pain on arteriovenous fistula cannulation: A narrative review.

Pain on arteriovenous fistula (AVF) cannulation is a rather persistent problem in the daily hemodialysis practice. Its prevalence varies from 12% to even 80% depending on the definition and the pain-assessment tools and it affects the quality of life of hemodialysis patients. It is associated with fear of the cannulation process, the decision of hemodialysis from an AVF and sometimes the hemodialysis itself. In this narrative review, we tried to tackle the extent of the problem and to present the available published solutions. The literature suggests a large array of methods based on the application of local anesthetic creams, application of cold or hot directly on the cannulation sites or on the contralateral arm, cannulation techniques and AVF localization, distraction as well as alternative treatments. All of them have shown a relative success. There is a serious lack of large multicenter randomized trials and a gap concerning work groups and guidelines or recommendations from national or international societies on this matter. Complementary training starting from the predialysis patient education programs may be useful. Alternative prophylactic measures including counseling, hypnosis, or other physicochemical interventions could also improve our knowledge on the treatment of this seriously uncomfortable condition.

Methods based on a semi-empirical model for simulating scroll compressors with HFC and HFO refrigerants.

The aim of this work is to evaluate three methodologies regarding semi-empirical scroll compressor modeling for different refrigerants and conduct a comparative analysis of their results and accuracy. The first step is to improve a semi-empirical model for scroll compressors based on established techniques, and further enhance the physical background of some of its sub-processes leading to more accurate predictions. Focus is then given on the compressor operation when changing the refrigerant, proposing three methods in total. The first method refers to the standard model, requiring an optimization process for the calibration of all the model parameters. The second method relies on a reference refrigerant, and also uses optimization procedures, but for the fine-tuning of a small subset of the parameters. The third method is more generalized, without the need of any optimization process for the parameters identification, when fluid change occurs, leading to a very fast approach. Το evaluate the accuracy and verify the applicability of each method also related to the necessary computational time, two scroll compressors each with three different refrigerants are considered (HFCs and HFOs and their blends). The model is evaluated with the available manufacturer data, using R134a as reference refrigerant. The results show that the first method predicts the key indicators with a very high accuracy, with the maximum discrepancy of 2.06%, 4.17% and 3.18 K for the mass flow rate, electric power and discharge temperature respectively. The accuracy of the other two methods is dropping, but within acceptable levels in most of the cases. Therefore, in cases that reduced accuracy can be accepted, the third method is preferred for compressor performance prediction when changing the refrigerant, which provides results at a small fraction of time compared with the other two methods, once the parameters are calibrated for a reference case.

Extracorporeal photopheresis for the treatment of graft rejection in 33 adult kidney transplant recipients.

Background - Extracorporeal photopheresis (ECP) has shown encouraging results in the prevention of allograft rejection in heart transplantation. However, the role of ECP in kidney transplant (KT) rejection needs to be determined. Methods - This multicentre retrospective study included 33 KT recipients who were treated with ECP for allograft rejection (23 acute antibody-mediated rejections (AMRs), 2 chronic AMRs and 8 acute cellular rejections (ACRs)). The ECP indications were KT rejection in patients who were resistant to standard therapies (n = 18) or in patients for whom standard therapies were contraindicated because of concomitant infections or cancers (n = 15). Results - At 12 months (M12) post-ECP, 11 patients (33%) had a stabilization of kidney function with a graft survival rate of 61%. The Banff AMR score (g + ptc + v) was a risk factor for graft loss at M12 (HR 1.44 [1.01-2.05], p < 0.05). The factorial mixed data analysis identified 2 clusters. Patients with a functional graft at M12 tended to have cellular and/or chronic rejections. Patients with graft loss at M12 tended to have acute rejections and/or AMR; higher serum creatinine levels; DSA levels and histologic scores of AMR; and a longer delay between the rejection and ECP start than those of patients with functional grafts. Conclusions - ECP may be helpful to control ACR or moderate AMR in KT recipients presenting concomitant opportunistic infections or malignancies when it is initiated early.

Constipation in Peritoneal Dialysis Patients.

Constipation in peritoneal dialysis (PD) is an infrequent but potentially serious condition affecting the mechanical properties of dialysis techniques and predisposing to bacterial intestinal translocation and eventual enteric peritonitis. Despite the importance of the problem, published literature is scarce, consisting mostly of uncontrolled single-center trials. This inconsistency may be attributed to the large number of clinical, radiological, and endoscopic tools that have been used in the studies with a lack of generally accepted core primary outcomes.The current narrative review discusses the pathophysiological associations between chronic kidney disease, PD, and constipation with related complication.

Gastrointestinal Disorders in Peritoneal Dialysis Patients.

BACKGROUND: Gastrointestinal (GI) disorders in peritoneal dialysis (PD) patients are relatively understudied in the literature, even though they have a serious impact in the morbidity parameters and the quality of life for this group of patients. Various diagnostic tools have been used, including instrumental methods and questionnaires, invariably validated in comparative studies. SUMMARY: The prevalence of GI disorders is very high in PD patients. Compared to the haemodialysis patients they present a higher prevalence of reflux, eating dysfunction, gastroesophageal reflux, intestinal obstruction or adhesions and abdominal hernia. They may be divided into Gastric disorders (Gastroesophageal reflux disease, pathological Gastric emptying, Dyspepsia, Helicobacter pylori infection, peptic ulcers) and Intestinal disorders (Peritonitis, Diverticulosis, Constipation). Key Messages: The current paper is a review of the literature involving GI disorders in PD patients. This special group of patients with a special role of the peritoneal cavity and the GI motility in the physiology of their dialysis merit a larger number of studies dealing with the interrelation of the GI tract and the PD physiological, functional and pathophysiological parameters.